Can you insert a pre existing ASP .NET website into SharePoint 2010?

You can do one of two things:

1) Host the other web application on the same server, but in a different web application in IIS on a different port or different host header.

or

2) Repurpose the code from the web application into SharePoint web parts and add them to a SharePoint site.

will i be able to use sharepoints features in my site if i go with option 1?

will i be able to use sharepoints features in my site if i go with option 1?

No.

It would operate as an independent application and you would only have access to SharePoint content if you wrote it into the application to use the SharePoint web services, etc.

Im looking to write with ASP .NET and c#.

Could I do that if I went with option 2?

Im looking to write with ASP .NET and c#.

Could I do that if I went with option 2?

could i create it in vs first, then copy code over to sharepoint?

You create it completely in VS and then deploy your code to SharePoint.

In VS you will be creating a web part class library that contains all of your code.  It will generate a DLL file that you will deploy the SharePoint.  The tutorial will walk you through that.

would be nice if i could just write an ASP .NET web page and somehow be able to run it through the SharePoint environment without having to create web parts.

To recreate an entire web page into web parts and then recreating a large website on top of that will not help.

The 2 should be easy to integrate.

Thanks for the help...I think I will leave SharePoint alone for now.

You can run them separately and take advantage of SharePoint features in the web application through the web services SharePoint has to offer, but it wouldn't be fully integrated as you are looking to do.